Sustainable Chemical Engineering

Microstructure and Compressive Strength of Geopolymer Materials Based on Metakaolin with Hematite and Magnetite Gels as Additives

2024-04-09T17:48:06+08:00

The purpose of this work is to increase the compressive strength and improve the microstructure of geopolymer materials by adding hematite and magnetite gels, as well as their powders, cured at 80 °C. Hematite and magnetite are dissolved in 10 M sodium hydroxide. Dried gels of hematite and magnetite were then ground to produce powders of dissolved hematite and magnetite. For the production of various geopolymer materials, the metakaolin was replaced by 0 and 10 wt. % of each additive and then mixed with the hardener containing the SiO₂/Na₂O molar ratio set at 1.6. The results show that the reference geopolymer has a compressive strength of 51.11 MPa. These values are 50.99 and 47.59 MPa for the geopolymer materials with 10 wt. % of dissolved magnetite gel and the powder of dissolved magnetite cured at 80 °C, respectively. They are 59.52 and 63.23 MPa for those prepared using 10 wt. % of dissolved hematite gel and for the powder of dissolved hematite cured at 80 °C, respectively. Si, Al, Fe, Na and Ti form a homogeneous phase in the geopolymer structures with the exception of a few magnetite particles agglomerated in the geopolymer materials. Compressive strength was found to be improved by the use of hematite gel and dissolved hematite powder cured at 80 °C as additives. A slight reduction in the compressive strength was observed when the dissolved magnetite gel and the powder of the dissolved magnetite cured at 80 °C were used as additives.

Enhanced Biodiesel Production from Waste Cooking Oil Using Potash-Enriched Natural Base Catalyst

2024-04-25T14:11:24+08:00

The transesterification reaction of waste cooking oil with methanol using a sugar apple peel ash catalyst has been reported. Under optimized conditions, the reaction of the oil with methanol in a molar ratio of 1:10, in the presence of a catalyst (2 g) at 60 °C temperature offered a 94.5% yield of biodiesel within 120 min. The heterogeneous catalyst was developed via a straightforward calcination process using fruit processing industry waste peels of sugar apples. The characterization of the catalyst by FTIR, EDS, SEM, XRD, N₂ sorption, and XRF analysis revealed a higher concentration of potassium species which is possibly responsible for the promotion of the transesterification reaction more efficiently. This approach offers cost competitiveness, reusability of the catalyst, simplicity of operation, and high biodiesel yields. This study underscores the potential of utilizing waste materials for sustainable biodiesel production, contributing to environmental preservation and economic viability.

Enhancing the Cu (II) Removal in Water Using Functional Hybrid Membranes

2024-01-26T08:56:13+08:00

This work developed hybrid EIPS/NIPS membranes of poly (butylene adipate-co-terephthalate) (PBAT) with nanocurcumin (NC) and/or Cloisite 20A (C20A). The dispersed phases were characterized by dynamic light scattering (DLS), ζ potential, X-ray diffractometry (XRD), scanning electron microscopy (SEM), and fourier-transform infrared spectroscopy (FTIR), while XRD, SEM, FTIR, mechanical properties, contact angle, and copper sorption evaluated the composite membranes. DLS analysis indicated that the dispersed phases present a nanometric size distribution; ζ potential measurements showed low electrostatic stability, explaining the agglomeration effects observed. Pure PBAT membranes presented macro-pores throughout their structure, which showed a slight size reduction with the inclusion of NC and C20A. The membrane’s mechanical performance was affected by the presence of the pores that functioned as stress-concentrating defects, and the inclusion of the dispersed phases increased the elastic modulus and tensile strength, especially for PBAT/0.5% C20A with values 18.7 and 8.9% higher than those of pure PBAT, respectively. Hybrid EIPS/NIPS membranes showed a hydrophilic nature with all the contact angle measurements lower than 90°. The sorption tests using a high-concentration copper solution (1,000 mg/L) showed a removal of around 25%. These results highlighted the development of new eco-friendly membranes using NC and C20A as dispersed phases with the potential to remove toxic elements from water.

Sustainable Management of Forest and Building Wastes for Hydrogen- Rich Syngas from Catalytic Steam Gasification with Minimum CO₂ Emissions

2024-04-01T08:35:37+08:00

The current study aimed at the exploitation of forest residues and their industrial waste for biofuel production, together with the exploitation of building demolition wastes (BDW) for CO₂ capture from the gasification process. Selected materials were gasified by steam in a fixed bed unit, using BDW as sorbent and CeO₂ and K₂CO₃ as catalysts. The effects of sorbent/biomass ratio, catalyst loading and temperature on final conversion, product gas composition and heating value, syngas and hydrogen yield and energy recovery were examined and optimum conditions were determined. Analysis of gases was performed in a thermogravimetric-mass spectrometric (TG-MS) system. At a ratio of Ca/C = 1, the amount of CO₂ captured at 750 °C was 73.2-76%, the concentration of hydrogen in the product gas was 56.2-59.3% mol and the higher heating value was 13.1 MJ/m³. An increase of catalyst loading up to 20% wt resulted in higher conversion and syngas and hydrogen yields. K₂CO₃ catalyst showed a better overall performance. In this case, conversion ranged between 80.7% and 84.8%, the molar fraction of hydrogen in the product gas was 67-80.5%, syngas yield varied from 1.9 m³/kg to 2.6 m³/kg, with a heating value of 13.1-13.8 MJ/m³ and energy recovery was higher.

Sustainable Starch Strategies: Nano and Macro Adsorbents for the Detoxification of Synthetic Dyes and Heavy Metals

2024-04-19T16:23:24+08:00

The research being conducted explores environmentally friendly techniques for heavy metal and synthetic dye detoxification from aquariums via nano- and macro adsorbents based on starch. In exposure to the urgent demands for sustainable wastewater treatment solutions, the research effort focuses on the development and evaluation of materials made from starch that have enhanced adsorption abilities. The effectiveness of developing and evaluating macro- and nano-sized starch composites and starch-based adsorbents in facilitating the elimination of heavy metals and synthetic colours is determined. The review includes a thorough examination of equilibrium traits kinetics, and adsorption processes, also takes into account how these sustainable starch-based products could be employed in real-world environmental remediation scenarios. The aforementioned findings offer significant additional knowledge regarding how to develop and implement starch-based adsorbents for the long-term and effective detoxification of heavy metals and synthetic colours compared to water.

Morphological, Thermal, Physicomechanical and Optical Properties of Crosslinked Poly (Ester-Urethane-Acrylate): Effect of Added Methyl Methacrylate

2024-03-06T15:49:10+08:00

Poly (ester-urethane-acrylate) (PEUA) macromonomer was prepared by reacting two moles of isophorone diisocyanate (IPDI) with one mole of bis (1,4-butanediol ortho-phthalate) (BPE), followed by end-capping with two moles of 2-hydroxyethyl methacrylate (HEMA) in the presence of dibutyltin dilaurate (DBTDL) catalyst. Thereafter, different ratios of methyl-methacrylate (MMA) were added to the PEUA macromonomer to prepare crosslinked PEUA/MMA sheets. Fourier transform infrared spectrometry (FTIR), ultraviolet-visible spectrophotometry (UV-vis) and differential scanning calorimetry (DSC) techniques were employed to investigate the structure, optical transparency and thermal properties of the crosslinked sheets. The effect of MMA on the polymerization shrinkage and abrasive wear properties of PEUA and their copolymers were also studied. The polymerization shrinkage study showed that PEUA copolymer containing 40 wt% MMA had a more rigid microstructure with improved volume shrinkage and abrasive wear properties as compared with the other compositions of PEUA copolymers with MMA loadings of 80, 60 and 20%. The improvement was attributed to the better miscibility and compatibility of 40 wt% MMA with the PEUA as revealed by DSC, heat deflection temperature (HDT) and scanning electron microscope (SEM) studies.

Design and Mechanical Analysis of a Continuous Stirred Tank Reactor (CSTR) for the Optimum Operation and Production of Propylene Glycol from Propylene Oxide Hydrolysis

2024-05-09T16:05:38+08:00

This study aimed to optimize the production of propylene glycol by designing a continuous stirred tank reactor (CSTR) and analyzing its thickness. The research involved developing a reaction kinetic scheme and mass and energy balance models to determine key reactor functional parameters and account for temperature effects. Simulation results for a yearly production of 400,000 tons of propylene glycol showed a reactor volume, height, diameter, spacetime, space velocity, and heat generation per unit volume at maximum conversion and operating temperature of values 62.08 m³, 6.81 m, 3.41 m, 2,608.70 s, 0.00038 s^-1, and -1.30 J/m³s, respectively. The relationship between fractional conversion, operating temperature, and reactor functional parameters was presented, while the mechanical design of both the CSTR column and stirrer was considered. The study recommended a thickness specification of 23 mm for an ellipsoidal-shaped column head made from stainless steel material type 304 due to its ability to withstand operating conditions. CSTR design and its thickness analysis are crucial for the optimum production of propylene glycol because they ensure the proper mixing of reactants and prevent heat loss during the exothermic reaction. This leads to increased reaction efficiency, higher yields, and improved product quality. Results showed that proper CSTR design and thickness analysis are essential for optimal propylene glycol production for domestic and industrial applications.

Review of Sulfate Removal in Low Concentration Brine Solutions

2024-05-17T14:15:28+08:00

Sulfate is a common ion present in natural water bodies at low concentrations and as effluent in different metallurgical processes. The discharge of sulfate in rivers and waterbodies can cause direct and indirect damage to the environment. Regulatory agencies have been increasing the constraints in sulfate content limit for discharge focused on human equity and environmental protection. A common practice is the precipitation of sulfate with lime, but the remaining solution still has ca. 1,500 mg L^-1 of sulfate, which is not acceptable for disposal or reuse. This work describes the main routes for sulfate removal such as chemical precipitation, biological degradation, ion exchange, and separation through membranes and discusses the main advantages and issues of each approach. One of the main challenges is to scale up the tests and show the performances at the industrial level. The subject must be the focus of constant study to obtain relevant results so that usual technologies are replaced by more innovative, cheap and efficient methods.

Computational Approach for Architecture, Tailoring, and Advancements in Perfluorinated Compounds: Synthesis, Characterization, and Future Directions in Fire Suppression Technology

2024-04-01T09:10:31+08:00

The demand for effective fire extinguishants has spurred investigation into novel perfluorinated molecules due to their exceptional properties, including high thermal stability, low toxicity, and eco-friendliness. This study presents a computational framework for designing and tailoring perfluorinated compounds as potential alternatives to traditional extinguishing agents. The research centers on elucidating the synthesis, molecular architecture, and characterization of these compounds to enhance their fire suppression capabilities while mitigating environmental impact. By employing computational methods, molecular modeling, and advanced spectroscopic techniques, the structural intricacies and potential applications of perfluorinated compounds in fire suppression are investigated. Additionally, future research directions aimed at addressing challenges and advancing the development of environmentally sustainable fire extinguishants are discussed. This manuscript contributes to the ongoing efforts to replace conventional extinguishing agents with safer and more environmentally friendly alternatives.